Test tube tray feed mechanism

ABSTRACT

A load advancement mechanism characterized by a slip coupling driven by a constant speed gearmotor coacting with an initial torque imposed by a constant tension spring to advance a load engaging arm at a constant speed to a stop and further adapted to be retracted manually by pulling back on the arm.

United States Patent [191 ,Uci. M, WW3

[ TEST TUBE TRAY FEED MECHANISM 3,208,058 9/1965 Brehm et al. 242/107 75] Inventor: Joe K. Bain, Decatur, Ala.

5 Primary Examiner-Charles J. Myhre 73 Assignee; Micromedic Systems, Inc Assistant Examiner--Wesley S. Ratliff, Jr.

philadelp'hiq Att0rneyCarl A. Castellan and George W. F. 221 Filed: on. 19, 1971 [21] Appl. No.: 190,486 [57] ABSTRACT [52] U S C 74/89 22 64/30 R 267/156 A load advancement mechanism characterized by a [51] Int Cl n Flush 27/02 Slip coupling driven by a constant speed gearmotor co- [58] Fieid 64/30 R, acting with an initial torque imposed by a constant /156 '254/l07 tension spring to advance a load engaging arm at a constant speed to a stop and further adapted to be re- 56] References Cmd tracted manually by pulling back on the arm.

UNITED STATES PATENTS 11 Claims, 2 Drawing Figures 3,491,602 l/l970 New 267/156 2,638,762 5/1953 Rayner 64/30 A TEST TUBE TRAY FEED MECHANISM This invention relates to a test tube tray mechanism which utilizes a constant force spring and a slip coupling to provide a constant force moving at a constant speed to facilitate the movement of a tray carrying loaded test tubes.

One of the main problems in advancing and moving trays of test tubes or trays carrying liquid samples has been the speed and force at which said trays are moved. Too great a speed or acceleration will tend to spill liquids carried by containers received in the tray.

Various solutions have been proposed to the aforementioned problem and among them is an inertia loading concept. This concept involves attaching an inertial load to a spring driven shaft and to utilize the delay and start-up time to slow the rate of travel of a tray or load and hence limit the impact as it contacts a stop. Such an approach is unsatisfactory since the velocity, even though limited, is always greatest at the end of the load movement. Further it involves a compromise in inertial load size to accommodate varying load weights.

Other approaches have involved wound-up springs. With such a spring the force arm is retracted and the spring is woundup as the force arm is gradually retracted. The further back the arm is pulled the greater the force. The arm then is simply released against the load and forces it forward. Such an approach is unsatisfactory because the spring constant is critical when intangibles like friction are considered. A spring strong enough to advance a load at the worst frictional condition and maximum load wieght is unsatisfactory under conditions of minimum force requirement. Further an accidental release of the arm several inches away from the load will impact the load with enough force to on occasion cause load spillage. An additional disadvantage is that the arm would be unduly hard to pull back.

A further approach has involved viscous damping with a spring. This concept involves attaching the force arm to an escapement or viscous damping device to slowly advance the load. This approach is not satisfactory because of the time delay from the time the arm is released until it contacts the load should it be pulled further back than necessary.

The instant device overcomes all the aforementioned disadvantages and provides a light constant force when the force arm is released and moves against the trays carrying test tubes. It is applicable to one to five tiers of trays and avoids sloshing and spillage of the liquid contained in the test tubes or containers. Whenever trays are required to be moved forward as determined by a tray sensing switch and logic, which do not form part of this invention, a driving force is provided by a constant speed gearmotor which insures the proper final position of the trays without sloshing or spillage. When the feed or force bar or arm is manually retracted a minimum pull force is required. The force arm can be locked in the rearmost position by a latch or similar device.

Accordingly it is an object of this invention to provide an efficient tray feed mechanism which eliminates spillage in tubes or containerscarried by the trays and which does not necessitate a large pull back force.

Another object of this invention is to provide a tray feed mechanism which provides a light contact force when the force arm is released and moves against trays carrying containers of liquids.

A further object of this invention is to provide an improved tray feed mechanism which is adapted to move trays containing test tubes at a constant speed toward a processing station. These and other objects of this invention will become apparent when reference is taken to the following specifications and accompanying drawings in which:

FIG. 1 is a perspective overall view of the tray feed mechanism constituting this invention;

FIG. 2 is a cross-sectional view taken along lines 2--2 of FIG. 1.

Referring now to FIG. 1, the mechanism is shown generally designated as 10. The apparatus in which the mechanism is employed has a planar surface designated as 12. A pair of upstanding bracket members 14 and 18 support the mechanism. The bracket members are supported by angle members such as 16.

Mounted on bracket member 14 is a gearmotor 20 having mounting tabs such as 22 through which pass mounting screws 24. Gearmotor 20 drives a shaft 26 on which is mounted slip coupling 28. Slip coupling 28 has hubs 29 and 30 and spring 32. Hub 29 is fixedly secured to shaft 26 and hub 30 is fixedly secured to shaft 26'. It is understood that shaft 26' extends through hub 30 and extends into a bore (not shown) in hub 29 and terminates therein.

Mounted on shaft 26 for rotation therewith is a pulley 34 having a circumferential groove 36 therein for receiving a cable 38, one end of which is fixed in a suitable manner (not shown) in the pulley groove. Also mounted on shaft 26' for rotation therewith and adjacent pulley 34 is disc 40 on which one end of a constant tension spring 42 is attached (not shown) and wound. The other end of spring 42 is attached to and wound as at 42' on pulley disc 48 which is mounted for rotation on shaft 44 and secured thereon by keeper 46.

The other end of shaft 26' is mounted for rotation in a bore (not shown) in bracket 18.

Cable 38 is trained around a pulley 52, as at 38', mounted for rotation on shaft 50 and having groove 58 and pulley 56 mounted for rotation on bolt 54 and having groove 60.

A cable housing and rack arm guide 62 is secured to a wall 64, which acts as a stop in the mechanism. Wall 64 may be separate and only as high as housing 62 or may be coextensive with wall 18'.

Cable 38 extends within housing 62 and is coupled, adjustably, in any suitable manner (not shown) to a narrow projecting portion (not shown) of arm 68. The narrow projecting portion of arm 68 is slidingly received within a slot 66 in the side of housing 62. Thus, arm 68 is able to slide longitudinally toward wall 64 for the length of slot 66.

Arm 68 has a narrowed tapered portion 70 and a relieved area 72 to enable a user to grasp the arm to pull it away from wall 64.

Arm 68 slides on the rounded heads of machine screws 86 which are received within apertures in arm 68 as shown in FIG. 2. To maintain the head portions 82 a sufficient distance from the underside of arm 62, resilient washers such as 84 are fastened thereto by screws 46.

In the alternative, (not shown) a wheel or caster may be mounted in or under arm 68 and supported therein by a pin for rotating support thereof. Also, wheels or rollers may be rotatingly mounted on a vertical axis in the front edge of arm 68 for rolling engagement with a load, such as a test tube rack 74. As shown, test tube rack 74 has a plurality of tube receiving apertures such as 76 for receiving tubes such as 78.

Referring to slip coupling 28 which includes shafts 26 and 26, hubs 29 and 30 and spring 32, the unit is typical of many commercially available slip couplings. The unit serves as a torque limiter and has a long life under continuous slip conditions.

The mechanism provides light contact force, about one-quarter pound, when the feed arm 68 is released and moves against test tube trays such as 74 which may number as many as five in adjacent relationship, thus avoiding sloshing and spillage of the liquid in tubes 78. When the trays are required to be moved forward, as determined by a tray sensing switch (not shown) in the apparatus, a driving force in the order of 4 pounds is provided by constant speed gearmotor which insures the proper final position of the trays without sloshing and spillage. When arm 68 is retracted a manual force of 4 pounds is required. The arm locks in the rearmost position, as shown in FIG. 1, by a small latch (not shown). It is released by depressing a small plastic button (not shown) connected to the latch.

In operation, the arm 68 is accelerated to the load or tray 74 and hub is slipped at 8 oz-in. slip torque counterclockwise relative to hub 29 of slip coupling 28 by torque T, (10.4 oz-in.) developed by the constant force spring 42. When gearmotor 20 is energized by the transporter or apparatus electronic logic (not shown) for a time interval, i.e., 3 sec., the tray 74 is advanced at constant speed to a stop provided by the tray(s) abutting wall 64 or the end of slot 66, a two second time interval, by torques T and T When the stop is reached, hub 29 is slipped at 32 oz-in. of slip torque, counterclockwise relative to hub 30 for the remaining one second time interval by torque T Arm 68 is retracted to its initial position by manually overunning torque T,, 10.4 oz-in., and 32 oz-in. coupling slip torque. Coupling 28 is a wrapped spring assembly which slips at different torques dependent on rotation direction. Hub 30 slipped counterclockwise is 8 oz-in. slip torque, clockwise is 32 oz-in. slip torque.

As previously stated, the assembly can be used in an apparatus used to test blood or urine samples contained in test tubes. In such a device, once the trays engage wall 64, an advance mechanism would be triggered and the trays would move laterally along wall 64 at 90 to their prior direction of movement.

While only one embodiment has been shown and described it will be obvious to those skilled in the art that many changes and modifications may be made without departing from the scope of the appended claims.

What is claimed is:

1. A tray feed mechanism for advancing a tray carrying liquid-containing tubes comprising a generally flat surface means, first and second stop means spaced along said surface means, an arm guiding means extending between said stop means, an arm means mounted for movement along said arm guiding means between said stop means, means normally biasing said arm means toward said second stop means and differential means adapted to move said arm means and an adjacent tray toward said second stop means at a constant speed for a predetermined time interval whereby spillage of the liquids in the tubes does not occur during movement of the tray.

2. A mechanism as in claim 1, wherein said differential means comprises a motor and a slip coupling having two hubs, a first shaft connecting said motor and one hub of said coupling, second shaft means coaxial with said first shaft means and connected to the second hub, pulley means on said second shaft, flexible means connected at one end to said arm means and to said pulley means at its other end, and power means for driving said motor.

3. A mechanism as in claim 2, wherein said biasing means includes a constant force spring, one end of said constant force spring being wound around said second shaft and attached thereto, a third shaft means, a pulley on said third shaft means, the other end of said spring being wound around said pulley and attached thereto whereby said spring provides a constant force on said arm through said flexible means.

4. A mechanism as in claim 3, wherein said coupling includes a wrapped spring connection and wherein said second hub is adapted to slip in one direction of rotation at a lesser torque than in the opposite direction of rotation relative to said first hub.

5. A mechanism as in claim 1, wherein said mechanism includes a latch means adapted to maintain said arm means at said first stop position.

6. A mechanism as in claim 1, wherein said guide means has a slot therein and said arm means'has a projecting portion extending therethrough and adapted to ride in said slot.

7. A mechanism as in claim 6, wherein said arm means has bearing means mounted on the underside of said arm means and adapted to support said arm means as it moves on said surface means and a relieved area in said arm means whereby an operator may grasp said arm means and retract it to said first stop position.

8. A mechanism as in claim 1, wherein said biasing means includes a constant tension spring and said differential means includes a slip coupling and motor means.

9. A mechanism as in claim 8, including a flexible cord means and wherein said biasing means and coupling means are connected to said arm means by said flexible cord means.

10. A device for advancing a receptacle to a station for the withdrawal or receipt of a filling material comprising a supporting surface adapted to receive the receptacle resting in freely movable respect on the surface, means for guiding the receptacle along a path of movement, means for advancing the receptacle in the path comprising a member for pushing the receptacle along the path, a drive shaft, a driven shaft, a slipclutch connecting the two shafts, a flexible cable having one end connected to the member, and spring means associated with the driven shaft for normally biasing the member in the direction of advancement, and stop means for limiting the movement of the receptacle in its path.

11. A mechanism as in claim 2, wherein said power means is adapted to run said motor for a predetermined time that is longer than, the period required for the tray to reach a position abutting the second stop means. 

1. A tray feed mechanism for advancing a tray carrying liquidcontaining tubes comprising a generally flat surface means, first and second stop means spaced along said surface means, an arm guiding means extending between said stop means, an arm means mounted for movement along said arm guiding means between said stop means, means normally biasing said arm means toward said second stop means and differential means adapted to move said arm means and an adjacent tray toward said second stop means at a constant speed for a predetermined time interval whereby spillage of the liquids in the tubes does not occur during movement of the tray.
 2. A mechanism as in claim 1, wherein said differential means comprises a motor and a slip coupling having two hubs, a first shaft connecting said motor and one hub of said coupling, second shaft means coaxial with said first shaft means and connected to the second hub, pulley means on said second shaft, flexible means connected at one end to said arm means and to said pulley means at its other end, and power means for driving said motor.
 3. A mechanism as in claim 2, wherein said biasing means includes a constant force spring, one end of said constant force spring being wound around said second shaft and attached thereto, a third shaft means, a pulley on said third shaft means, the other end of said spring being wound around said pulley and attached thereto whereby said spring provides a constant force on said arm through said flexible means.
 4. A mechanism as in claIm 3, wherein said coupling includes a wrapped spring connection and wherein said second hub is adapted to slip in one direction of rotation at a lesser torque than in the opposite direction of rotation relative to said first hub.
 5. A mechanism as in claim 1, wherein said mechanism includes a latch means adapted to maintain said arm means at said first stop position.
 6. A mechanism as in claim 1, wherein said guide means has a slot therein and said arm means has a projecting portion extending therethrough and adapted to ride in said slot.
 7. A mechanism as in claim 6, wherein said arm means has bearing means mounted on the underside of said arm means and adapted to support said arm means as it moves on said surface means and a relieved area in said arm means whereby an operator may grasp said arm means and retract it to said first stop position.
 8. A mechanism as in claim 1, wherein said biasing means includes a constant tension spring and said differential means includes a slip coupling and motor means.
 9. A mechanism as in claim 8, including a flexible cord means and wherein said biasing means and coupling means are connected to said arm means by said flexible cord means.
 10. A device for advancing a receptacle to a station for the withdrawal or receipt of a filling material comprising a supporting surface adapted to receive the receptacle resting in freely movable respect on the surface, means for guiding the receptacle along a path of movement, means for advancing the receptacle in the path comprising a member for pushing the receptacle along the path, a drive shaft, a driven shaft, a slip-clutch connecting the two shafts, a flexible cable having one end connected to the member, and spring means associated with the driven shaft for normally biasing the member in the direction of advancement, and stop means for limiting the movement of the receptacle in its path.
 11. A mechanism as in claim 2, wherein said power means is adapted to run said motor for a predetermined time that is longer than the period required for the tray to reach a position abutting the second stop means. 